The present invention pertains generally to the field of cooling systems for electronic apparatus. In particular, the invention is believed to have its greatest applicability in the field of high speed digital electronic computers, and the description herein of the presently preferred embodiment of the invention illustrates the use of the invention in the computer field.
The supplying of adequate cooling to electronic equipment is a constantly recurring design problem which has prompted many solutions and cooling techniques over the years. When forced air cooling failed to provide adequate heat transfer, the circulation of liquid coolants was adopted. When faced with still higher heat loads, designers have turned to refrigeration cycle equipment, with the evaporator unit being located within the chassis area adjacent the electronic modules or components.
Ever increasing developments in the field of electronic circuitry miniaturization have not alleviated thermal design problems in electronic equipment. If anything, further miniaturization has had the opposite effect, because the smaller size of components and the combining of multiple components in integrated circuits have allowed a greater number of devices to be packed into a smaller physical area. The combined heat dissipation of thousands of miniature circuits packed into a small physical area can easily exceed the heat transfer capabilities of cooling systems which were successful with prior art electronic implementations.
This thermal problem is most intensely felt in the field of high speed electronic digital computers. Increasing sophistication in the complexity and data handling size of computers has greatly increased the number of required circuit modules for logic and memory. Further, for reasons related to providing a desired high speed of operation, the type of circuitry used in high speed computers is not the circuit type having the lowest heat dissipation. Further complicating the problem is the fact that the short clock periods required for high speed data processing place constraints on the physical length of connecting wires within the central processor. This in turn implies that the greater number of circuits required for logic and memory in the largest and fastest machines must be packaged with a higher circuit packaging density than was the case with slower and less complex prior art machines.
In the face of these thermal problems, prior art refrigeration cooling systems for computers have not proved adequate. One example of a prior art refrigeration cycle electronic cooling system is shown in U.S. Pat. No. 3,334,684. In that patent, cooling bars having internal refrigerant flow paths are spaced along a chassis, and each cooling bar has a plurality of transverse aluminum plates. These plates define individual compartments therebetween, and the circuit modules are placed therein. Although the type of construction represented in prior U.S. Pat. No. 3,334,684 provides adequate cooling up to a certain point, it will not provide the quantity of heat transfer required in newer computer designs. One problem with the construction shown in the prior patent is the relatively large air gap between the circuit module and the aluminum plates. A second problem is the relatively long heat conducting path from the extremities of the aluminum plate down to the cooling bar which contains a refrigerant flow. Yet another problem is the difficulty of inserting and replacing individual modules.